In a wide variety of technologies, the ability and/or facility for separating matter, typically particulate matter, from a fluid is a critical component in the ability to test for the presence of substances in the fluid. Too often, interference associated with sample preparation obscures the target cells to such a degree that the process is not sufficiently reliable, or too costly.
Such a scenario applies to many other fields which involve detection and/or diagnosis, including environmental testing, radiation research, cancer screening, cytological examination, microbiological testing, and hazardous waste contamination, to name just a few.
In all of these endeavors, limiting factors in the sample preparation protocol include adequately separating particulate matter from its fluid carrier (e.g., physiological fluid, biological fluid and environmental fluid), and easily and efficiently collecting and concentrating the particulate matter in a form readily accessible for microscopic examination.
In the case of cytological examination, a sample of cells is obtained from a patient. Typically, this is done by scraping or swabbing an area, as in the case of cervical samples, or by collecting body fluids, such as those obtained from the chest cavity, bladder, or spinal canal, or by fine needle aspiration. In a conventional manual cytological examination, particulate matter including cells and debris in the fluid are transferred onto a glass slide by smearing and subsequently air-dried. Smearing results in non-uniform densities and uneven distributions of cells and debris that often obscure the target cells. Air drying causes cell distortion and further impedes accurate examination.
It has been found that prompt processing of urine to obtain fresh ensures the accuracy of quantitative culture results, urinalysis and microscopy. Fresh cells tend to stick to a glass slide much better than cells from preserved urine, allowing for smoother cell spread onto the glass body. Delays in processing, negligent care in either inpatient or outpatient settings and lack of refrigeration may lead to non-optimal slide preparation. One known solution to the delay problem is the use of chemical preservatives with the urine. The presence of liquid preservatives, however, in the urine specimen raises the specific gravity of the specimen to unmeasurable levels and may limit the potential usefulness of the urine for various types of traditional quantitative analysis, such as slide microscopy.
Diagnostic microbiology and/or cytology, particularly in the area of clinical pathology, bases diagnoses on a microscopic examination of cells and other microscopic analyses. The accuracy of the diagnosis and the preparation of optimally interpretable specimens typically depends upon adequate sample preparation. New methodologies such as immunocytochemistry and image analysis require preparations that are reproducible, fast, biohazard-free and inexpensive. Conventional cell preparation techniques fail to adequately address the issues of non-uniform cell densities, uneven cell distribution and air drying artifacts.
Conventionally, body fluid samples are collected for cytological examinations using containers that contain a preservative solution for preserving the cytology specimen during shipment from the collection site to the cytology laboratory. Furthermore, cytology specimens collected from the body cavities using a swab, smear, flush or brush are also preserved in containers with fixatives (e.g., alcohol or acetone fixatives) prior to transferring cells onto the slide or membrane for staining or examination.
It is desirable to provide a urine or other biological fluid specimen container that would allow liquid biological specimens to be tested without removing the lid of the urine or biological fluid container. However, none of the prior art solves the problems of transferring cells in a monolayer to a slide for examination without submerging portions of the device in the sample (and increasing the risk of contamination), consistently and repeatedly forming a high quality monolayer on the microscope slide, and processing the sample so that the fluid from which the cells were taken is preserved.
A number of methods, apparatuses, and structures for dispersing cells in the fluid are known. For example, U.S. Pat. No. 5,143,627 opens the sample container, inserts a dispersing element into the liquid suspension, and rotates the dispersing element for several minutes. In another example, the so-called "Saccomanno method" is used to process sputum, a process that is time consuming and involves a large number of processing steps.
In contrast to the conventional techniques, the solid matter preparation techniques of the present invention address the issues of non-uniform matter densities, uneven matter distribution, and sample loss and contamination due to the number of steps involved in the sample preparation. Thus, preparations according to the present invention result in an even distribution of solids that have superior morphology, improved visualization, and are readily positioned and available for light absorbance analysis without the need to further manipulate or prepare the sample.